Axial piston variable displacement hydraulic units utilize a tiltable swashplate to control the displacement of pistons within a rotating cylinder block. One common type of tiltable swashplate is a cradle type swashplate which is supported at one end of the housing by a pair of arcuate bearings having rolling elements. This pair of roller bearings are spaced apart in a transverse plane to permit the passage of a shaft coupled to the cylinder block. Each of the pair of roller bearings is provided with a retainer locating the individual rollers of the bearing. Common roller bearing practice requires that the arcuate displacement of the roller bearing cage be one half of the arcuate displacement of the cradle swashplate in order to obtain an exclusively rolling motion of the roller elements. Furthermore, since the roller bearings are arcuate, but not totally circular, repeated tilting of the swashplate can lead to slipping of the roller elements between the housing and the cradle swashplate to positions other than the desired optimum support positions for resisting the axial thrust of the swashplate.
In order to assure that the part arcuate roller bearings do not slip to an adverse position, limit stops have been secured to either the swashplate or the housing such as taught in Lucien U.S. Pat. No. 3,631,764. However, this solution does not assure the desired one half displacement relationship of the bearing cage relative to the swashplate. Therefore, locating means which do provide such one half displacement relationship have been provided. These locating means can be gears such as taught in Baits U.S. Pat. No. 3,396,670, pivotal pins such as taught in Schwede et al U.S. Pat. No. 4,029,367, or pivotal levers such as taught in British Pat. No. 231,917 issued Apr. 7, 1925. However, since there are a pair of roller bearings involved, each of these prior art solutions require the use of a pair of spaced apart locating means for the respective roller bearing cages. This duplicates the expense of the locating means and, furthermore, unduly complicates the assembly of the unit.
It is furthermore known in the general roller bearing art to place two roller bearing assemblies in side by side relationship with a single cage acting as a retainer for the rollers of both bearing assemblies. Such cages have been formed of both steel and plastic. In the latter form, two plastic retainers of a linear or flat double row bearing are joined by two thin plastic webs permitting the pair of rows to be bent to a desired angle between each other.